Light diffraction on metal gratings under conical incidence by the true-mode method

A microstructured metallic surface gives rise to a number of interesting visual effects which can advantageously be used is security elements. The modeling of such effects is still an open issue as far as 1D periodic structures under conical incidence and 2D structures are considered. The true-mode method has the potential of becoming a reference method for such difficult electromagnetic problems. This was already demonstrated in 1D gratings under collinear incidence. It will soon be demonstrated in the case of 2D metallic gratings. On the way to this objective we are reporting here on the implementation of the true-mode method for conical incidence on ID-metal gratings.